Gas turbine components can consist of multiple details secondarily bonded with structural adhesives to provide a strong durable bond that meets service requirements. These structures can consist of composite bonded to composite, composite bonded to metal or metal bonded to metal. It is desirable that the most expensive and complex details be designed for full service life and considered reusable while the composite or metallic details designed for partial service life are considered expendable and replaceable.
Adhesively bonded structures required to survive high loading events, e.g., bird strike, must have a structurally capable, durable bond generally negating the concept of using bonding practices designed to weaken the interface. When the expendable component is replaced, the adhesive remaining on the reusable component surface must be removed or prepared to allow bonding. The remaining adhesive is generally difficult to remove and requires mechanical action which increases the risk of damaging the part surface. The removal of the remaining adhesive is particularly difficult when component replacement is performed under field conditions with the jet turbine engine still attached to the aircraft. For this reason the ability of the remaining adhesive to be removable without mechanical action or chemical treatments is preferred.
In many cases the assembled gas turbine components require close dimensional tolerances to ensure proper alignment during further assembly operations and to provide an aerodynamic surface which meets design limits. When working with typical silicone paste adhesives the alignment of the replaceable component to the reusable component during the bonding operation is achieved by tooling which fixtures the components relative to the aerodynamic flow path surface. To reduce the complexity and cost of the tooling it is desirable to have an adhesive with a controlled thickness and limited flow. Additionally when working with paste adhesive the ability to apply the adhesive to the required areas at a controlled dimension requires skilled labor or equipment that can meter and place the adhesive. It is therefore desirable that the adhesive can be easily cut to shape before application and applied to the component with ordinary hand tools.
Therefore, there exists a need for an adhesive that does not require complex and costly tooling associated with prior methods.